The present invention generally relates to material transport apparatuses and, more specifically, pertains to a new and improved construction of a transport apparatus for the transport or conveyance of substantially flat structures products or articles, in particular continuously arriving printed products.
Generally speaking, the transport apparatus of the present development is of the type comprising a plurality of individually controllable gripper elements or grippers which are arranged in mutually spaced relationship in tandem or succession at a traction element which is revolvingly driven in a predetermined direction of transport or conveyance of the products. Each of the gripper elements or grippers comprises a clamping jaw and a clamping finger for engaging one of the edges of the continuously arriving flat structures, products or articles, especially printed products. The products generally are of the type which continuously arrive in an imbricated or shingled formation and the edges which are engaged or grasped by the gripper elements or grippers extend transversely with respect to the predetermined direction of transport or conveyance of the products.
Furthermore, each clamping finger extends essentially at right angles or orthogonally from a shaft or shaft member and can be selectively pivoted back and forth from an open gripper position where the clamping finger is directed transverse to the product conveying direction into a closed gripper position in which the clamping finger is directed in the product transport or conveyance or conveying direction. A closing or closure spring or spring member biases the clamping finger towards the clamping jaw.
A transport apparatus of the aforementioned general type is known from Swiss Pat. No. 468,923, granted Feb. 28, 1969 and the cognate U.S. Pat. No. 3,671,035, granted June 20, 1972. A threaded bushing arranged at an overhang or cantilever arm is provided with a female thread of large pitch. A shaft or shank is threaded into the female thread and a clamping finger protrudes at right angles from the shaft or shank. At the end region of the shaft, situated remote from the clamping finger, there is provided a laterally protruding slide shoe or at its end a slide shoe which is effective in axial direction of the shaft. A closing spring arranged about the shaft and the threaded bushing or sleeve bears at one end at the overhang or cantilever arm and at the other end at the associated slide shoe. When the laterally protruding slide shoe travels onto a stationary cam then the shaft is rotated.
Due to such shaft rotation and as a consequence of the provision of the thread or threading there also results lifting of the clamping finger from the clamping jaw. On the other hand, if the slide shoe travels onto a stationary actuation element, for instance a roll track, then the clamping finger is raised from the clamping jaw and due to the presence of the threading there results a pivoting or rocking of the clamping finger out of the closed position into the open position. Upon travel of the corresponding slide shoe off of the cam or the actuation element the shaft, under the action of the closing spring, moves towards the clamping jaw. This, in turn, results in a pivoting of the clamping finger into the closed position owing to the presence of the threading or thread. The angle of turning or rotation of the clamping finger and the shaft is dependent upon the thickness of the printed product which is to be fixedly held or retained. In order to positively retain printed products of different thicknesses, it is necessary that the free end of the clamping finger which is located remote from the shaft be designed to be quite wide. This in turn, requires a relatively large angle of rotation or turning of the clamping finger. Additionally, there exists the problem that the thread in the threaded bushing or sleeve and at the shaft must be exactly aligned with respect to the clamping finger. Such requires relatively complicated fabrication operations.
Moreover, if a gripper or gripper element is to be arranged at both sides of the traction element, then there must be employed threaded bushings or sleeves having both right-hand thread and left-hand thread, resulting in an increase in the number of different individual parts or components which must be provided for the construction of the transport apparatus.